Have you ever been with someone so content and excited about life that when you are with her you're on a higher plane than usual? But when she leaves your presence and you two are no longer together, you feel a certain "down" feeling and you are once left to find this feeling somewhere or with someone else. There's a big gaping hole you've left open my friend and that's due to the fact that you haven't found what makes you happy that you can call your own. 

A close friend of mine once said a relationship will work when both individuals have found happiness on their own and not rely on the other to provide that happiness. However, I felt that her definition was a bit incomplete and caused me to add a Team Capital mindset: make your life so great that you can walk away from anything or anyone that does not fit in with your own happiness--or something like that. In short, surround your life with things and people that give you the content and uplifting feelings. 

Things: When I say things I mean activities that provide you a lasting experience. I refrain to relying on material things like easily bought items in the form of shoes, clothes, etc., because they're only meant to give you that momentary feeling. Activities though, like working out, learning new skills, reading books, etc., not only provide you entertainment, but it allows you to share it with others and it creates growth in your life.

People: I must make the disclaimer that you should surround yourself with people that provide you growth through encouragement and a good dose of reality at times when you need it. What I don't want you to seek from people is their presence to get rid of your loneliness and their own life activities to fill your own lack of drive to do more than your own current affairs. People should complement  what you're already doing in your own life and not to fill that nagging void.

Whatever you decide to fill your happiness, understand that when it's barren you end up looking elsewhere for it to be filled. When those items you fill it with can't be called your own then they end up escaping your jar and you're left to continue looking to fill it once more. When you truly find your jar almost being filled to the brim, you can reach in anytime and smile because you can be still wherever you are and know that whoever leaves you or whatever thing doesn't work out is not going to affect you. Like I said, your happiness is already right there so being unhappy isn't even in the picture.